From the Guidelines
Yes, shingles (herpes zoster) can cause encephalopathy, which is a brain dysfunction that can manifest as altered mental status, confusion, or cognitive impairment. Shingles is caused by the varicella-zoster virus (VZV), which can spread to the central nervous system in some cases, as noted in studies such as 1. This neurological complication is more common in immunocompromised individuals, such as those with HIV/AIDS, cancer patients on chemotherapy, or organ transplant recipients on immunosuppressive medications. The virus can directly infect brain tissue or trigger an inflammatory response that affects brain function.
Key Considerations
- The presentation of encephalitis caused by VZV can be acute or sub-acute with fever, headache, altered consciousness, ataxia, and seizures, as described in 1.
- Reactivation of VZV may also lead to encephalitis, especially in the elderly or the immunocompromised, with an insidious onset and sometimes no zoster rash, fever, or CSF pleocytosis, as noted in 1.
- Treatment typically involves high-dose intravenous antiviral medications like acyclovir (10-15 mg/kg every 8 hours for 14-21 days), valacyclovir, or famciclovir, along with supportive care, as recommended in 1 and 1.
- Early diagnosis and treatment are crucial to prevent long-term neurological damage, with the dosage of acyclovir in patients with normal renal function being 10 mg/kg intravenously every 8 h for 14–21 days, as specified in 1.
Important Recommendations
- Patients with shingles who develop headache, confusion, seizures, or behavioral changes should seek immediate medical attention, as these may be signs of encephalopathy or other neurological complications.
- Acyclovir should be initiated in all patients with suspected encephalitis as soon as possible, pending results of diagnostic studies, as advised in 1.
- The use of adjunctive corticosteroids may be considered in some cases, although the evidence is not yet conclusive, as discussed in 1 and 1.
From the Research
Herpes Zoster and Encephalopathy
- Herpes zoster, also known as shingles, can cause encephalopathy, as evidenced by several studies 2, 3.
- Encephalopathy is a condition characterized by brain disease, damage, or malfunction, and can present with symptoms such as altered mental status, confusion, and disorientation.
- Herpes zoster-associated encephalitis (HZAE) is a rare but serious complication of herpes zoster, and can occur in both immunosuppressed and non-immunosuppressed individuals 3.
Clinical Findings and Treatment
- The clinical findings of HZAE include disturbances of mental function, ataxia, and nuchal rigidity, as well as abnormal spinal fluid findings and EEG results 3.
- Treatment with acyclovir has been shown to have a beneficial effect in patients with HZAE, with rapid resolution of symptoms and normalization of EEG results 2.
- However, acyclovir can also cause neurotoxicity, particularly in patients with renal impairment or those who are immunocompromised, which can present with symptoms similar to HZAE 4, 5.
Key Considerations
- Differentiating between HZAE and acyclovir neurotoxicity is crucial, as the management of these conditions is vastly different 5.
- Patients with herpes zoster should be closely monitored for signs of encephalopathy, and treatment with acyclovir should be initiated promptly if HZAE is suspected 3.
- The use of valacyclovir and acyclovir in patients with renal impairment or those who are immunocompromised should be done with caution, due to the risk of neurotoxicity 4, 5.